Addition of 177Lu-PSMA-617 to enzalutamide improves PSA-PFS in mCRPC

Interim results from the phase 2 ENZA-p study (NCT04419402) show that adding 177Lu-PSMA-617 to enzalutamide significantly enhances prostate-specific antigen progression-free survival (PSA-PFS) in patients with metastatic castration-resistant prostate cancer (mCRPC), according to findings presented at the 2023 ESMO Congress.

“This is the first randomised trial combining an androgen receptor signalling inhibitor, enzalutamide, with 177Lu-PSMA-617. It provides strong evidence for an enhanced anti-cancer effect with the combination of enzalutamide and 177Lu-PSMA-617 based on the primary end point, PSA-PFS,” said study co-author Dr Louise Emmett, Director of Theranostics and Nuclear Medicine at St Vincent’s Hospital in Sydney, Australia.

Data from the study showed a median PSA-PFS of 13 months with the combination therapy compared with 7.8 months with enzalutamide alone [HR 0.43; 95% CI, 0.29-0.63; P=.00001]. Median radiographic PFS was 16 months with the combination therapy compared with 12 months for enzalutamide alone [HR 0.67; 95%, CI 0.44-1.01].

Furthermore, PSA 50 per cent (decrease ≥50 per cent from baseline) response rates were 93 per cent (77/83) in the combination arm, compared with 68 per cent (54/79) for enzalutamide alone (P<.001). PSA 90 per cent (decrease ≥90 per cent from baseline) response rates were 78 per cent (65/83) among those in the combination arm compared with 37 per cent (29/79) among those who received enzalutamide alone (P<.001). In total, the ENZA-p study included 162 patients with mCRPC.

Median follow-up among all patients included in the study was 20 months. There is planned follow-up of PFS and overall survival in the study until July 2024.